Didymodon vinealis
Didymodon perobtusus
didymodon moss, soft-tuft beard-moss
didymodon moss
leaves often twisted, appressed to weakly spreading or spreading-flexuose when dry, spreading to spreading-recurved and not keeled when moist, monomorphic, lanceolate, grooved adaxially along the costa, especially near leaf apex, 0.8–2.5(–4) mm, base scarcely differentiated to oblong in shape, margins recurved below mid leaf or to above mid leaf, entire, apex acute, not fragile, commonly ending in a conical cell;
costa percurrent or more commonly short-excurrent, not strongly spurred, not much widened or tapering, lacking an adaxial pad of cells, adaxial costal cells quadrate to short-rectangular, ca. 4 cells wide at mid leaf, guide cells in 1(–2) layers;
basal laminal cells differentiated medially or across the leaf, walls thin to weakly thickened, rectangular or seldom quadrate, not perforated;
distal laminal cells 7–10 µm wide, 1:1, nearly smooth or papillae simple or 2-fid, 2–3 per lumen, lumens irregular or oval to rounded-quadrate, walls thin or evenly thickened, convex on both sides of lamina, 1-stratose or occasionally 2-stratose in patches.
leaves appressed-incurved when dry, weakly spreading and not keeled when moist, monomorphic, ovate-lanceolate, broadly concave adaxially across leaf, usually 0.7–1.2 mm, base weakly differentiated in shape, ovate, margins weakly recurved at mid leaf, minutely crenulate, apex rounded-acute, often weakly cucullate;
costa ending (2–)4–6 cells below the apex, not strongly spurred, little tapering, without an adaxial pad of cells, adaxial costal cells quadrate or short- to long-rectangular, 2 cells wide at mid leaf often grading to 4 proximally, guide cells in 1 layer;
basal laminal cells differentiated medially, walls thin or thick, quadrate to rectangular, not perforated;
distal laminal cells 9–11 wide, 1:1, papillae absent visible or low, simple, 1 over each lumen, lumens subquadrate to irregular, walls evenly thickened, weakly convex on both sides of lamina, 1-stratose.
0.8–1 cm.
only perichaetial plants seen.
1.5–2.5 mm;
peristome teeth 32, linear, twisted 1/2 to once, to 1300 µm, occasionally rudimentary or absent.
9–12 µm. Distal laminal KOH reaction light to dark red-brown, occasionally deep red-orange.
asexual reproduction very rare, by multicellular gemmae in clusters in leaf axils.
asexual reproduction by mostly unicellular gemmae in leaf axils.
unknown.
laminal KOH reaction red.
Didymodon vinealis
Didymodon perobtusus
Varieties 2 (2 in the flora).
Didymodon vinealis is often difficult to distinguish from sterile forms of D. rigidulus, but the elongate cells commonly found on the adaxial surface of the costa near the boat-shaped leaf apex, the often strongly papillose laminal cells, and the usual presence of a distinct groove down the adaxial surface of the leaf along the costa are characteristic features. Some but not all specimens may be quickly assigned to this taxon by a unique deep slit floored by elongate cells on the adaxial surface of the costal apex (the adaxial epidermis being absent), visible as a clear window abaxially. Bryoerythrophyllum recurvirostrum is immediately distinguished by the clear, enlarged proximal cells. Like Bellibarbula recurva, small forms of D. vinealis may have quadrate or very short-rectangular proximal cells and sinuose costa, but the former has thick-walled proximal cells and the costa twists laterally, not vertically in the concave distal portion of the leaf of D. vinealis, and the adaxial cells of the costa of commonly elongate, 2:1 or more.
(Discussion copyrighted by Flora of North America; reprinted with permission.)
Didymodon perobtusus is an extremely rare species known in the flora area from only two stations: Northwest Territories, Mackenzie District, Nahanni National Park, Virginia Falls, Scotter 22433 (NY); and Yukon, Firth River basin, near mouth of Mancha Creek, 68°40’N, 141°W, Sharp MC-58152a pro parte, 1958 (NY). It has several characters in common with D. revolutus of the southwestern United States and Mexico, including leaf and laminal papillae shape and unicellular gemmae borne in dense axillary clusters; however, D. revolutus differs by the strongly recurved to revolute margins, leaf cells with thin, light yellow walls, and gemmiferous plants uncommon, the propagula all unicellular. Both North American collections seen were from stations at which D. subandreaeoides is also present, growing in separate or occasionally confluent cushions. The taxonomic position of D. perobtusus is not clear. It is here placed near D. subandreaeoides because of dark, reddish color and similarity of areolation and laminal papillae. It may, however, turn out to be related to D. tophaceus, with which it has a certain resemblance.
(Discussion copyrighted by Flora of North America; reprinted with permission.)
1. Peristome present, well developed, cells of operculum twisted | var. vinealis |
1. Peristome absent, cells of operculum straight or nearly so | var. rubiginosus |
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